I thought major updates were when Google changed the name ICS to jb to kk...
This ended up being a little rant-y, so i apologise ahead of time. Not directed at anyone, just my general feeling toward the naming system.
The names are just marketing IMO.
4.1, 4.2, and 4.3 were all called jellybean, yet they each got their own press event, each got new devices released alongside them, and each brought some decent new features.
If you peel back the thin veil, with 4.2 Google started reporting their usage numbers not by android version number, but by version name.
Now everyone running "jellybean"(4.1.0-4.3.1) gets lumped in and reported together. Something they had previously only done with say 4.1.0-4.1.2.
This had huge implications for everyone crying fragmentation, because it allowed Google to say "jellybean" had the most market share, even though that spanned devices released and upgraded over an entire year rather than the 6 month cycle used previously
So ultimately...What's in a name?

Most developers** will go by version number, and according to that these releases are all just as "major".
**I don't count myself as one of those fine folks